Heater



FIG. 1 is a perspective view depicting the heater embodying my new design;

FIG. 2 is a front elevational view depicting the embodiment of FIG. 1;

FIG. 3 is a left elevational view depicting the embodiment of FIG. 1; and,

FIG. 4 is a top plan view depicting the embodiment of FIG. 1.

The broken line showing is included for the purpose of illustrating portions of the article that form no part of the claimed design. 

The ornamental design for a heater, as shown and described. 